Control of fluid pressure devices



Jan. 7, 1936. R. E'RLING 2,02 7,356

CONTROL 0F FLUID PRESSURE DEVICES Filed March 13, 1954 VIII lvENOR y,

@Run-W 3M ATTOR Y Patented ,.Jan. 7, 19.36

UNlTED s'mfllis PATENT ol-Flcls ooN'rltL on Enum PRESSURE DEVICES I Ralph Erling, Alexandria, Va. Application March 1s, 1934, serial No. 115,297 ioolaims. (Gnomes) (Filed but not issued under the 'act of March s, 1883, as amended April so, 192s; 37o o. G. 757) This invention relates to means for and a method of controlling the working of iiuid prespurpose specied, a compact assembly wherein the control actuating means and the pressure 'device itself are enclosed in a common housing structure.f

Invthe drawing: Fig. 1 is a longitudinal section of one such pres- ,sure device taken on the line I|, Fig. 2

Fig. 2 is a section at right angles to Fig. 1 on the line 2 2, Fig. 1;

Fig. 3 is an enlarged detail of a piston used in applying pressure in the device to aid in moving the controls thereof;

y Figs. 4 and 5 show two methods of applying 'my invention to pumps of the rotary control type.

I have shown, in the drawing, my invention specically applied to a variable delivery pump with radial pistons, and toy azvariable delivery pump with axial pistons, but it is applicable in general to all fluid pressure devices having means to vary the effective working capacity thereof, which means must be operated againstthe pressure in the device acting on the parts thereof affected by the controlmechanism. v

A constant speed prime mover, represented by the motor 4, is connected to drive a member 5 rotatably mounted in a main housing 6 that constitutes a portion of. the enclosing structure for the mechanism. A plurality of radially extending cylinders 1 are fox-med in member 5 with their axes lying in a common plane -at right angles to the axis of member 5 and in each cylinder a piston 8 is slidably disposed. A pair of rollers 9 is r0.- tatably mounted on each piston at the outer end thereof, which rollers bear against the face of a track I0 and are constrained to follow a race defined by members II that lie against the rollers 91on their radially inner sides.- Disposed within the member 5 and/coaxial therewith is a fixed member I2 havingrcut away portions I3 forming ports that are separated by a wall 50, each of which is in communication with a duct I4. The

track member Il) has plane surfaces I5 formed thereon to slide upon plane surfaces I6 in housing 3 to guide the member I0 when shifted parallel to the axial plane of pistons 8. Asis well known,

when the member I0 is concentric with member 3 rotation of. the last-named member produces no wardly moving pistons.

effect upon the pistons, but when the member I0 is moved to a position that is eccentric with respect to member 6 the pistons 8 are causedto move inwardly during one half a rotation and outwardly during the other half thereof, huid 5 being taken into the cylinders from the port I3 that is in communication with the outwardly moving pistons and then discharged under pressure into the port that communicates with the inl0 It is apparent that when the member i0 is in the concentric,.or neutral, position very little effort is required to shift it, but as 'soon as it is notably displaced from such neutral position the inwardly moving pistons apply pressure to the 15 uid and react against the member IIlin a direction opposite the displacing movement.

One phase of my invention relates tov applying the pressure within the pump to aid in moving the member I0 against this reaction, which is ac- 20 complished by the mechanism now vto be described. Fixed to main housing 6, either integrally or by suitableA fastenings, is an auxiliary housing I1 having in its spaces I8 and I9 in communication with ducts I4 and Ill', respectively, 25 and having also an inturned portion 2U tted upon an enlarged extension 2i of the fixed member l2, within which enlarged extension is a cylinder 22 communicating with the spaces I8 and I9 by ports 23 and 24, respectively. A shuttle valve 25 slid- 30' able in cylinder 22 is moved by the pressure'of fluid entering the cylinder through either of the ports 23 or 24 in such direction that the fluid always passes out through port 26. 1

In an auxiliary housing 21, likewise carried by 35 main housing 6, is disposed a bevel gear 28 having teeth engageable with a pinion 29 that is part of a follow-up system such as is well known in the art in the control of steering gear, gun turrets, hydraulic presses, etc. Two pinions 30 are rotat- 0 ably mounted upon gear 28 adjacent the center. thereof in diametrically opposite positions'to en? gage a gear 3l on shaft 32 that carries hand wheel 33 and also in'mesh with internal gear teeth of a rotatable member 34, which has in one portion 45 an aperture provided with threads to engage the threaded shank 35 xed to member I0, the aforesaid several gears constituting a differential gear mechanism( It is apparent that rotation of wheel system the rotation of member v34 will be the algebraic sum of the movements of hand wheel 33 55 and pinion 39.

Assoon as. member `Ill has been shifted off center by means of hand wheel 33 and the cooperating gear, stroke is put on the pistons 8 and further movement of member I0 must be 00 effected against the reaction of pistons 8 on member 8. To avoid placing the entire eiort of thus moving the member l0 upon hand wheel 33, I have provided the piston 36 connected to member 0 by a connecting'rod 31 and operably mounted in cylinder 38 carried by housing 6. In the wall of cylinder 38 is provided a port 39 that is connected, by means of a suitable pipe, to port 26, the inner mouth of port 39 being slightly less than the length of piston 36 and so disposed that when member I8 is concentric with member 5 the mouth oi' port 39 is closed by piston 36. To outlet ports 48 and 4 I separated by a cylinder wall element 42, are provided in another part of the wall of cylinder 38 and are in communication with the interior of housing 6 by a duct 43. The lateral face of piston 36, adjacent ports 48 and 4|, is provided with elongations 44 and 45, and ducts 46 and 41 are formed from the end faces of piston 36 to that part of the lateral face of the piston adjacent ports 40 and 4|, the distance between the respective outermost walls of these ducts where they open on the side of the piston being somewhat greater than the width of element 42, whereby, when the piston 36 isin the neutral position, each end ofthe cylinder 38 is in communication with duct 43, but as soon as displaced from such neutral, or mid-position, the duct communicating with that end of cylinder 38 from which the piston is moving is closed by element 42; while the duct on the other side of the piston remains open into its respective port 40 or 4|. It is easily seen that when the member I8 is in neutral position and there is no stroke on the pump, the port 39 will be closed by piston 36 and both ends of the cylinder 38 are in communication with duct 43, but when the member I8 is displaced from such neutral position and stroke is put on the pump, the piston 36 will be moved to open port 3s to admit uuid under pressure from the pump to cylinder 38 to act upon piston 36 in a direction that will aid .in moving the member against the reaction of the pump, regardless of the direction of such displacement and that at' the time of opening of valve 39 the duct on that side of the piston 35 to which pressure will be applied is closedby'element 42. The piston 36 need not be connected directly to the 'member lll as shown but may be connected to act through the member 34, veither including or excluding the rest of the differential gear mechahnism Figs. 4 and 5 show two methods of applying the principle of my invention to a variable delivery Pump of the axial piston type. In-the former figure the shaft 5| is vconnectible at 52 to a prime mover and has ilxed to its other end to rotate therewith a member 53 wherein are formed cylinders 54,' the pistons 55 in cylinders 54 being connected by piston rods 56 to a member 51 that is pivoted at 56 to shaft 5|. The control spindle 59, which is connected to manual control means and follow-up mechanism in a manner common in this art, extends through pump housing 60 and is connected inside the housing to a member 6| that rotates with spindle 58 about the axis oi.' the spindle, being held in operative position by gudgeons 62. When spindle 59 is rotated the member 6| is caused to assume a position at an angle to shaft 6| which constrains the pistons 55 to move into cylinders 54 during one half of each revolution and to move outwardly duringJ the other half thereof. The fluid, usually oil, that is utilized t0 transmit the pressure developed in the pump passes into the pump and out therefrom through ducts 63.

In communication with ducts 63 by ports 64 is a cylinder 22 in which is a shuttle -valve 25 to cause the iluid always to flow from cylinder 22 through port 26 to which ls connected a pipe 65 that transmits pressure to a cylinder 38 to act upon a piston 36, the parts of this piston and cylinder being in all respects the same as in the case of the like numbered elements in Figs. 1 and 2 and having the same mode of operation. The piston 38 in Fig. 4 is connected to actuate a lever-65 connectedI to control spindle 59 and thereby aid in displacing member 6| to vary the stroke of pistons 55.

pressure device to'aid in varying the effective' working capacity thereof and that by building all the mechanism into a. single, enclosing structure I have greatly smpliiied the construction, elim--I inated a number of mechanical connections, and eii'ected considerable economy of space necessary to accommodate the mechanism.

It is to be understood that the drawings forming a part of this speciilcation areillustrative only and not limiting, since the principle herein disclosed may be applied to other.,types of mechanisms than the variable delivery pumps speciilcally shown. a

'I'he inventionv described herein may be manufactured and used by or for the Government ci the 'United States of'America for governmental purposes without the payment of any royalties thereon or therefor.

I claim: y

1. 'Ihe combination with a iiuid pressure device having a cylinder, a piston therein, and movable means acting on said piston to vary the stroke thereof in said cylinder, of manually actuata'ble means for operating said movable means, and mechanism actuatable by iuid subjected to the pressure exerted in said cylinder connected to operatesaid movable means, said mechanism including an element having a neutral position wherein it prevents access of fluid under pressure to said mechanism, said element being mechanically connected to said manually actuatable means tobe moved by operation of said manually actuatable means to admit tluid to said mechanism in a direction to aid in the operation of said movable means.

2. The combinaton with a fluid pressure device having a cylinder, a piston therein, and movable means acting on said piston to vary the stroke thereof in said cylinder, of control means for operating said movable means, and-mechanism operatively associated with said movable means having'parts acted upon by fluid subjected to the pressure exerted in said cylinder, one of said parts being settable to prevent the passage of fluid into said mechanism and having a mechanical connection to said control means whereby actuation of the control moves said one part tov a positionto admit fluid to exert on said movable means a force in opposition to that exerted by said piston upon said movable means.

3. The combination with a fluid pressure device having a rotatable member wherein are formeda plurality of cylinderaplstons Operable in said cylinders, and movable means adjustable with respect to said cylinders to effect movement of said pistons in said cylinders during rotation of said member and to vary the stroke of said pistonsl of manually actuatable means for operating said movable means, and mechanism actuatable by uid subjected to the pressure exerted in said cylinders connected to operate said movable means, said mechanism including an element having a position at which it prevents passage vo1! iiuid into said mechanism, said element being mechanically connected to the manually actuatable means to be moved by operation of the manually actuatable means to a position to admit uid into said mechanism to exert a force to aid said manual means to operate said movable means.

4. The combination with a fluid pressure device having a rotatable member wherein are formed a plurality of cylinders, pistons operable in said cylinders, and movable means adjustable with respect to said cylinders to effect movement o'f said pistons in said cylinders during rotation of said member and to vary the stroke of said pistons, of control means to actuate said movable means, and mechanism operatively associated with said movable means having parts acted upon by fluid subjected to pressure exerted in said cylinders, one of said parts having in it a passage to admit fluid under pressure thereto and a second part within the rst part movable to close said passage, said second part being connected to said movable means and also mechanically connected to the control means whereby actuation of the control means moves said second part to the passage closing position or away therefrom to apply to said movable means a force in opposition to that exerted by said pistons upon said movable means.

5. The combination with a piston pump having movable means to vary the piston stroke, and

manually operable means to actuate said movable means, of a piston operatively connected to said movable means, and means controlled by actuation of said manually operated means to admit uid under pressure to act on said piston, said piston being mechanically connected to-the manually operable means to be moved by actuation of said manually operable means to admit `fluid as aforesaid, or to prevent admission of said iiuid, the admission of fluid being always in a-direction to aid in moving said movable means to increase the piston stroke.

6. The combination with a piston pump having movable means to vary the pistonstroke, and control means to actuate said movable means, of a piston connected to said movable means to move therewith, and a cylinder in which said piston is slidable, said cylinder having an intake port and outlet ports connectible to said pump to subject said piston to the .pressure produced by said pump, said ports being so disposed that the intake port is closed by said piston when said'piston is in mid-position in said cylinder but is open when said piston is somewhat displaced from said midposition through moving with said movablemeans in response to manipulation of said control means, the outlet ports being partially open' when said piston is in said mid-position but otherwise respectively covered to close the outlet from the pressure end of said cylinder and uncovered to open the outlet from the other end of said cylinder, such opening of the ports effecting application of the pump pressure to said piston in a sense to aid manipulation of said control means.

7. The combination with a piston pump having movable means to vary the piston stroke, and manually operable means to actuate said movable means, of a piston operatively connected to said movable means, a portion of the lateral face of said piston being longitudinally extended, and there being a duct extending from each end face of said piston through the aforesaid portion of the lateral face, a cylinder in which said piston is i slidable, said cylinder having a port with its inner mouth of somewhat less width than the length oi.' said piston and a pair of ports disposed to be covered by the piston and said extended portion, the ports of said pair being separated by a cylinder wall element of somewhat less width than the distance between the outermost walls of said ducts at their outer ends, the said wall element being opposite the rst mentioned port.

8. The combination with a piston pump having movable means to vary the piston stroke, and manually operable means to actuate said movable means, of a piston operatively connected to said movable means, a portion of the lateral face o! said piston being longitudinally extended, said piston having ducts to permit leakage from both ends of the cylinder when the piston is in midposition in the cylinder and from that end of the cylinder nearest the piston when the piston is not in the mid-position, said cylinder having a port with its inner mouth of somewhat less width than the length of said piston and a pair of ports disposed to be coverable by the piston and said extended portion, the ports of said pair beingfseparated by a cylinder wall element somewhat less in width than the distance between the outermost walls of said ducts at their outer ends, the said wall element being opposite the first said port and disposed to cover the outer end of the duct opening into the end of said cylinder from which the piston is more remote when the piston is not in said mid-position.

9. In combination, an enclosing structure, within said structure a variable delivery pump having movable means to vary the power output of said pump, control means in said structure to actuate said movable means, and means responsive to the operation of said control means to apply the pressure in said pump to shift said movable means in the same sense as said control means acts-thereon, said responsive means including an element mechanically connected to the control means and movable thereby to prevent the action of the pressure upon said responsive means.

10. In a fluid pressure device, a piston having a portion of its lateral face longitudinally extended, and a duct extending from each end face thereof through the aforesaid portion of the lat- '00 eral face, a cylinder in which said piston is slidable, said cylinder having a port with its inner mouth of somewhat less width than the length of said 'piston and a pair of ports disposed to be covered by the piston and said extended portion, the ports of said pair being separated by a cylinder wall element of somewhat less width than the dis- -tance between the outermost portion of the walls RALPH ERLING. 

